Polyolefin resins are commonly used as a material for the insulation and the sheath layers of wires and cables. Recently a higher degree of flame retardance has been demanded in accordance with, for example, a vertical tray test, which can be referred to as the "70,000 Btu per hour" test. Flame retardants such as organic halogen compounds; flame retardant aids such as antimony trioxide; or flame retardant resins such as poly (vinyl chloride) and chlorinated polyethylene can be blended into polyolefins to render them flame retardant; however, these additives cause dripping, smoking, and/or the emission of harmful gases when subjected to burning, and can also cause metals to corrode.
To solve these problems, addition of inorganic flame retardants such as metal hydroxides to the polyolefin resins was proposed and the composition was applied as insulating and sheath layers to various wires and cables. This did not, however, solve the problem of drip or improve the vertical tray test to a commercially desirable extent.